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([2001:df0:0:200c:1063:266d:3cf0:ce5b]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7fc9c388f0bsm10006665a12.54.2024.12.03.10.21.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 03 Dec 2024 10:21:23 -0800 (PST) Message-ID: Date: Wed, 4 Dec 2024 07:21:46 +1300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] arch: m68k: Add STACKTRACE support To: Jean-Michel Hautbois , Geert Uytterhoeven Cc: linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, rostedt@goodmis.org References: <20241203-add-m68k-tracing-support-v2-0-77302097a9f4@yoseli.org> <20241203-add-m68k-tracing-support-v2-2-77302097a9f4@yoseli.org> Content-Language: en-US From: Michael Schmitz In-Reply-To: <20241203-add-m68k-tracing-support-v2-2-77302097a9f4@yoseli.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Jean-Michel, good work on adding On 4/12/24 06:21, Jean-Michel Hautbois wrote: > In order to use tracing, implement a basic arch_stack_walk() based on > the one in PowerPC. > Tested on a M54418 coldfire. > > Signed-off-by: Jean-Michel Hautbois > --- > arch/m68k/Kconfig | 6 ++++ > arch/m68k/kernel/Makefile | 1 + > arch/m68k/kernel/stacktrace.c | 70 +++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 77 insertions(+) > > diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig > index 793ab1e2762609725bbf793f6dffecfa3ecfff0f..6ba3238ba2c68acaf5974396739e629b09eee3ca 100644 > --- a/arch/m68k/Kconfig > +++ b/arch/m68k/Kconfig > @@ -40,6 +40,8 @@ config M68K > select UACCESS_MEMCPY if !MMU > select ZONE_DMA > select TRACE_IRQFLAGS_SUPPORT > + select ARCH_STACKWALK > + select ARCH_WANT_FRAME_POINTERS How much does that add to kernel size? It's only needed for debugging so some folks may prefer to save a little on code size (not to mention the extra frame pointer save on each call) ... Cheers,     Michael > > config CPU_BIG_ENDIAN > def_bool y > @@ -106,6 +108,10 @@ config BOOTINFO_PROC > Say Y to export the bootinfo used to boot the kernel in a > "bootinfo" file in procfs. This is useful with kexec. > > +config STACKTRACE_SUPPORT > + bool > + default y > + Any reason why you can't place the two 'select' statements in this conditional? > menu "Platform setup" > > source "arch/m68k/Kconfig.cpu" > diff --git a/arch/m68k/kernel/Makefile b/arch/m68k/kernel/Makefile > index 6c732ed3998b714a4842ee29c977550a61979779..cb02bcfe04c6b265fa97db9237395a262e649989 100644 > --- a/arch/m68k/kernel/Makefile > +++ b/arch/m68k/kernel/Makefile > @@ -23,3 +23,4 @@ obj-$(CONFIG_UBOOT) += uboot.o > > obj-$(CONFIG_EARLY_PRINTK) += early_printk.o > > +obj-y += stacktrace.o > diff --git a/arch/m68k/kernel/stacktrace.c b/arch/m68k/kernel/stacktrace.c > new file mode 100644 > index 0000000000000000000000000000000000000000..4c2fb6b0cf675ee5a3a21393a50603fea98a1b03 > --- /dev/null > +++ b/arch/m68k/kernel/stacktrace.c > @@ -0,0 +1,70 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +/* > + * Stack trace utility functions etc. > + * > + * Copyright 2024 Jean-Michel Hautbois, Yoseli SAS. > + */ > + > +#include > +#include > +#include > +#include > +#include > + > +static inline unsigned long current_stack_frame(void) > +{ > + unsigned long sp; > + > + asm volatile("movl %%fp, %0" : "=r"(sp)); > + return sp; > +} > + > +static inline int validate_sp(unsigned long sp, struct task_struct *task) > +{ > + unsigned long stack_start, stack_end; > + > + if (task == current) > + stack_start = (unsigned long)task_stack_page(task); > + else > + stack_start = (unsigned long)task->thread.esp0; > + > + stack_end = stack_start + THREAD_SIZE; > + > + if (sp < stack_start || sp >= stack_end) > + return 0; > + > + return 1; > +} > + > +void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, > + struct task_struct *task, struct pt_regs *regs) > +{ > + unsigned long sp; > + > + if (regs && !consume_entry(cookie, regs->pc)) > + return; > + > + if (regs) > + sp = (unsigned long) regs; > + else if (task == current) > + sp = current_stack_frame(); > + else > + sp = task->thread.ksp; > + > + for (;;) { > + unsigned long *stack = (unsigned long *) sp; > + unsigned long newsp, ip; > + > + if (!validate_sp(sp, task)) > + return; > + > + newsp = stack[0]; > + ip = stack[1]; > + > + if (!consume_entry(cookie, ip)) > + return; > + > + sp = newsp; > + } > +} >